A friend/colleague of mine came out with this today. I gave him my best sceptical look and told him that’s probably rubbish.
I thought about it and then suggested that this might come from the idea that if a person stops excercising but doesn’t stop eating the higher volumes of food that go with excercising then they will pile on weight/fat.
I am very sceptical that the human body will simply start floofing away your muscles the moment you take a break from resistance training. His myth seems to suggest that you should NEVER stop a regular excercise regime otherwise you’ll turn into a bag of bones and fat.
So is there ANY truth to this ?
I’ve been working out for 2/3 my life, and am a former college athlete, and I can say that you are BOTH right … in a sense. When you use resistance training you thicken muscle fibers, not add them. You have the same amount of muscle cells, they just get bigger. I’m less clear on whether fat cells are formed anew or just get bigger. But regardless, if you stop using weight training totally, eventually your muscle cells adjust to the lower demands on them by getting smaller.
HOWEVER … this does NOT automatically translate into getting fatter. Gaining fat depends on whether you consume more calories than you burn. If you stop lifting weight AND adjust your caloric intake downward an amount equivalent to what you had burned when you were lifting, your muscles will shrink, you will lose weight, but you will not gain fat.
The expression that muscle “turns to fat” comes about I think because most people don’t understand that resistance training burns calories, so if you stop training but keep eating as much as before, you will inevitably get fatter.
The health benefits of working your muscles are well-proven, so your friend is basically correct that you should do training of some sort for your entire life. How much depends on your ultimate fitness goals. But if you control your eating, stopping your resistance training does not make getting fatter inevitable.
I think this is a case of miscommunication when passing along information scenarios.
Given the scenario where a person was exercising regularly, and then stopped but maintained the same diet, the muscle mass “could be replaced” by fat. That is, as the muscles atrophy from less use, yet the same amount of food is being taken in (and no longer burned from the exercise), the excess would be stored as fat. Some of this fat may eventually start to collect where the muscle mass used to be.
The other aspect is that the fat fills out the flesh, so there is less definition from the muscles. The muscles may not have atrophied much, but they are less obvious to see.
I think the “myth” is one of those motivational type sayings: “stop exercising and your muscles will be replaced by fat” (assuming the person would not adjust their diet accordingly). And somewhere along the way, someone swapped in “turns to” for “will be replaced by”.
Or another way of looking at it, is “stop exercising and you will go from being a muscular looking person, to a fatter looking person”. The muscles may not have gone away, or even been replaced. But your appearance will not hide them.
Adipose (fat or ‘signet’) cells in humans tend to max out at about 180 micrometers. (It’s interesting, the larger ones tend to be more insulin-resistant than the smaller ones, which would contribute to the development of type II diabetes, in theory anyway). After that size, they’re just not real metabolically stable or efficient anymore.
So adipose cells fill to a maximum amount, then if more calories are to be banked, the body starts generating new adipose cells. This is much more labor-intensive to do, to create new cells rather than topping off old ones.
Which is why it’s so easy to regain lost weight than to put on new weight for the first time, at least as far as fat mass goes. All those empty cells are just waiting to fill up with fat. But if no empties are available, the body may decide it’s not worth the effort to make new cells, and just burn the calories (or otherwise waste them via excretion) instead.
But as has been pointed out, muscles do not turn to fat.
This is not the first time I’ve heard this. The notion is not that you lose muscle and gain fat, but the the muscle actually transforms to fat. The upshot is that becoming a body builder can make you fat. My source? An episode of MASH.
Harry Morgan isn’t a doctor, but he played one on TV. For shame.
My pet theory: when you stop training you don’t lose the muscle immediately and if you don’t change your diet, you start gaining fat. Over your already hypertrophied muscles which makes you look fatter than if you had started gaining weight skinny muscles. That;s why people get the impression that muscle turns to fat,
I don’t think the comment is intended to mean that muscle literally converts itself into fat (which it cannot, as has been mentioned). It is more a suggestion that if you work out frequently and then stop, you’ll get fat. I think there is some truth to this.
First, there’s a recent study that seems to support this. Last month a study came out that said inconsistent exercise causes accumulation of fat that is more difficult to lose. (cite). The upshot is if you are exercising regularly and then stop, you’ll put on more fat that will be harder for you to lose later. It suggests the possibility of counterproductive ‘yo-yo exercising’ just as there is ‘yo-yo dieting’.
Secondly, strength training causes increases in metabolism and appetite. That’s pretty well established. It’s my opinion, for what it’s worth, that if you work out heavily and then stop, your appetite and eating habits do not adjust proportionately to your decreased metabolism. So you tend to eat as if you’re working out heavily, but since you aren’t, that food is stored as fat.
Thirdly I think there is some confirmation bias in effect. Few people can maintain a heavy strength straining schedule or a competitive physique for their entire lives. For one thing, body fat accumulates as you get older, and also people ‘retire’ from active workouts. Thus, every muscular person you see is eventually going to get fatter, and some of them are going to get really fat. People tend to focus on these novel situations rather than the unremarkable condition of non-athletes getting fatter.
This seems like as good a place as any to inquire about another theory I’ve heard, and apologies if it’s been addressed.
Does a person burn more calories at-rest if they have a greater muscle mass? My father is suggesting weight training and strengthening exercises rather than quite as much aerobic exercise for this reason – it’ll make me stronger, even if it doesn’t increase my stamina, and I’ll burn more calories even when I’m just sitting around, making it easier to get into shape and stay that way.
I don’t have a cite, but every time this question comes up around here, the consensus is that it has little effect on resting metabolism - only on active metabolism. But ‘active’ can mean walking across the parking lot, so that’s still a good thing.
Another reason to incorporate different kinds of exercise is the more you train on a particular exercise, the more efficient your body becomes in this exercise, thus it burns less fat.
Here is a good page I like to cite if you are looking for some straightforward numbers on different exercise strategies: http://www.exrx.net/FatLoss.html
In particular I think the body composition studies section is very interesting.
I think you have these things out of order. People get fatter because they “retire” from exercising, as if it were something only for kids or “health nuts.” Exercise is not the thing in one’s life that is expendable when the schedule gets full; everything else is. It’s a scientific fact that people who follow this principle consistently live longer and better (healthier) lives. Unfortunately, Americans do not live this way, and we die younger as a result.
Look at Jack Lalanne, in his 90s and still working out like a madman. Who WOULDN’T want to be that healthy at his age? He’s living proof that getting fat as one ages is not inevitable. All it takes is effort. One does not need to train heavily, or maintain a “competitive” physique, but health does not maintain itself.